There is a lack of information on the initial events that occur in normal lung epithelial cells upon exposure to environmental tobacco smoke (ETS), a known carcinogen. Although biochemical markers, such as cell cycle state, glutathione (GSH) levels and cytokine secretion have been described for transformed lung cell lines and tumors., little information exists for primary human lung epithelial cells exposed to ETS. Furthermore, no genetic markers in ETS exposed normal human lung cells have been defined to predict tumorigenic potential. Therefore, this application proposes to characterize the biochemical markers, cell cycle state, GSH and cytokine levels, and to identify potential genetic markers of lung tumor development in normal lung epithelial cells due to ETS exposure. This will be accomplished by carrying out the following specific aims. Specific Aim I will determine the temporal profile of these biochemical markers in both primary human bronchial epithelial cells (HBEC) and small-airway epithelial cells (SAEC) exposed to ETS. Specific Aim II will determine the temporal expression profiles of 8,327 genes in HBEC and SAEC exposed to ETS. These profiles will be correlated with respect to cell type (HBEC versus SAEC), temporal changes and the biochemical tumor markers characterized in Aim I. Our hypothesis is that the gene array analysis of these cells will identify a set of genes whose altered expression is predictive of human lung cancer. This gene set coupled with the biochemical tumor markers will have a better predictive value of significant cellular alterations, which impact on the development of lung cancer due to ETS exposure. This approach will extend our knowledge of the effects of ETS on normal primary human lung epithelial, and provide a basis upon which to predict new relationships for genes whose expression is altered by ETS. Expression profiling is expected to provide a new approach for comparisons between normal and cancerous cells, as well as to suggest potential targets for intervention.